On Sun, Sep 3, 2017 at 10:55 AM, Commit Bot <b...@cloudius-systems.com>
wrote:
> From: Waldemar Kozaczuk <jwkozac...@gmail.com>
> Committer: Nadav Har'El <n...@scylladb.com>
> Branch: master
>
> Waldek Kozaczuk discovered that nginx, using sendfile(), is experiencing
> various failures when multiple concurrent connections are attempted.
>
Oops, I forgot the shortlog. Sorry about that....
I'll leave it like this, to avoid an even bigger mess in the repository.
> It turns out that sendfile() had the wrong return type: Should have been
> ssize_t (long), was int. So when sendfile() returned a -1, the application
> sometimes thought it was a positive 4294967295. Of particular interest to
> the nginx case, sendfile() is expected to temporarily fail when a non-
> blocking socket's buffer is full, and this is "error" path is part of the
> normal nginx operation, and did not happen correctly.
>
> The fix is of course to change sendfile()'s return type to ssize_t, to
> match
> Linux. Also in this patch we #include sys/sendfile.h to have the compiler
> check the function's signature (if we had this #include earlier, we would
> have caught this bug immediately).
>
> Signed-off-by: Nadav Har'El <n...@scylladb.com>
>
> ---
> diff --git a/fs/vfs/main.cc b/fs/vfs/main.cc
> --- a/fs/vfs/main.cc
> +++ b/fs/vfs/main.cc
> @@ -38,6 +38,7 @@
> #include <sys/statvfs.h>
> #include <sys/stat.h>
> #include <sys/time.h>
> +#include <sys/sendfile.h>
>
> #include <limits.h>
> #include <unistd.h>
> @@ -2007,8 +2008,7 @@ int lchown(const char *path, uid_t owner, gid_t
> group)
> }
>
>
> -extern "C"
> -int sendfile(int out_fd, int in_fd, off_t *_offset, size_t count)
> +ssize_t sendfile(int out_fd, int in_fd, off_t *_offset, size_t count)
> {
> struct file *in_fp;
> struct file *out_fp;
> @@ -2086,6 +2086,7 @@ int sendfile(int out_fd, int in_fd, off_t *_offset,
> size_t count)
> return ret;
> }
>
> +#undef sendfile64
> LFS64(sendfile);
>
> NO_SYS(int fchmodat(int dirfd, const char *pathname, mode_t mode, int
> flags));
>
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